(New) 19 May 2026, Computational Social Choice Seminar, Tomasz Wąs

Abstract

An index is a function that, given an election, outputs a value between 0 and 1, indicating the extent to which this election has a particular feature. We seek indices that capture agreement, diversity, and polarization among voters in approval elections, and that are normalized with respect to saturation. By the latter we mean that if two elections differ by the fraction of candidates approved by an average voter, but otherwise are of similar nature, then they should have similar index values. We propose several indices, analyze their properties, and use them to (a) derive a new map of approval elections, and (b) show similarities and differences between various real-life elections (including those from Pabulib, Preflib and other sources). This is joint work with Piotr Faliszewski, Jitka Mertlová, Krzysztof Sornat, and Stanisław Szufa.

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